Objectives of this research project are (1) to characterize the dispersion and dilution of gaseous and small-particle aerosol contaminants within a confined, ventilated space that simulates a biomedical research laboratory, or other work space, (2) to detect and describe any deviations from the theoretical phenomenon of perfect mixing of contaminant and air. For experimental parameters of ventilation rate, contaminant source location, and location of sample point, a tracer gas is released into a test space and real-time measurements of gas concentration are made and recorded. The data are statistically analyzed to (1) determine the spatial distribution of tracer gas concentration and test for homogeneity of concentration at the different sample points, (2) to determine the degree of mixing (measured by relative dilution rates) at each sample point and test for homogeneity of mixing at the different sample points. Results for combinations of the parameters are compared and analyzed. Experimental protocols will be developed for future studies of contaminant dispersion in laboratory and other work spaces under diverse conditions.